64-slice multidetector coronary CT angiography: in vitro evaluation of 68 different stents

Abstract

The purpose of this study was to test a large sample of different coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in 64-slice multidetector-row computed tomography (MDCT) in vitro and to provide a catalogue of currently used coronary artery stents when imaged with state-of the-art MDCT. We examined 68 different coronary artery stents (57 stainless steel, four cobalt-chromium, one cobalt-alloy, two nitinol, four tantalum) in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density -70). Stents were imaged in axial orientation with standard parameters: 32 x 0.6 collimation, pitch 0.24, 680 mAs, 120 kV, rotation time 0.37 s. Four different image reconstructions were obtained with varying convolution kernels and section thicknesses: (1) soft, 0.6 mm, (2) soft, 0.75, (3) medium soft, 0.6, and (4) stent-optimized sharp, 0.6. To evaluate visualization characteristics of of the stent, the lumen diameter, intraluminal density and noise were measured. The high-resolution kernel offered significantly better average lumen visualization (57% +/-10%) and more realistic lumen attenuation (222 HU +/-66 HU) at the expense of increased noise (15.3 HU +/-3.7 HU) compared with the soft and medium-soft CT angiography (CTA) protocol (p<0.001 for all). Stents with a lumen visibility of more than 66% were: Arthos pico, Driver, Flex, Nexus2, S7, Tenax complete, Vision (all 67%), Symbiot, Teneo (70%), and Radius (73%). Only ten stents showed a lumen visibility of less than 50%. Stent lumen visibility largely varies depending on the stent type. Even with the improved spatial resolution of 64-slice CT, a stent-optimized kernel remains beneficial for stent visualization when compared with the standard medium-soft CTA protocol. Using 64-slice CT and high-resolution kernel, the majority of stent products show a lumen visibility of more than 50% of the stent diameter.

Noninvasive Cardiac Imaging with Computed Tomography

“…25,28,[31][32][33][34][35][36][37][38] MSCT allows an accurate, non-invasive evaluation of the coronary vessels in those at intermediate risk for CAD. As stated previously, MSCT scanners also provide a coronary artery calcium score.…”

“…8,27,35 Large diameter stents (>3 mm) and those with thinner struts improve the accuracy for detecting and quantifying in-stent restenosis with MSCT. 37 Furthermore, use of high-resolution "kernels", or specific reconstruction algorithms, can improve in-stent evaluation by fine-tuning image resolution. 37,38 Still, only evaluation of stent patency is possible with an adequate diagnostic accuracy.…”

“…37 Furthermore, use of high-resolution "kernels", or specific reconstruction algorithms, can improve in-stent evaluation by fine-tuning image resolution. 37,38 Still, only evaluation of stent patency is possible with an adequate diagnostic accuracy. A reliable assessment of stent stenosis cannot be expected.…”

Image Post-Processing and Interpretation

“…Different stent compositions and structures appeared to be associated with variations in the extent of residual artifact. The use of special reconstruction algorithms improved visualization of the stent lumen and reduced blooming artifact with a drawback of a modest increase in noise in the images (Maintz et al, 2006).…”

Coronary Stent Artifact Reduction With an Edge-Enhancing Reconstruction Kernel - A Prospective Cross-Sectional Study With 256-Slice Ct

“…Most studies performed to assess the effect of sharp kernels in coronary CT stent imaging were done in vitro [9][10][11][12][13][14][15][16][17]. Only few in vivo studies have quantitatively evaluated the effect of CT kernels on coronary stent artifacts [18][19][20].…”